Mill hammer with removable tip



Aug. 5, 1952 c. LE BLANC 2,605,972

MILL HAMMER WITH REMOVABLE TIP Filed March 29, 1951' Inventor.

Patented Aug. 5, 1952 MMTEQ. 'STATES PATENT GFFECE MILL HAMMERWITH REMovABL-Trr Charles Ille Blanc, Montreal, Quebec, Canada Application March 29, 1951, Serial No. 218,112() The present invention relates to hammer mills and more particularly to a mill hammer with a removable Working tip.

Hammer mills used for crushing stones and ores such as in the manufactureA of cement, generally consist in a horizontal or vertical shaft, rotating at high speed, on which is mounted, either rigidly or pivotally, one or more crushing elements which may consist of hammers or 'the like.

Such hammers, although made of a material highly resistant to shock, wear out very rapidly due to the considerable abuse to which they are subjected, consequently they have to be replaced rather frequently and therefore constitute a rmajor item in the operating expenses of the mill.

Moreover, because suchv hammers are relatively heavy and have a substantial volume, the housing of the hammer mills have to be partly dismantled for removing such hammers thereby Aprolonging unduly the stoppage of the mill- According, the general object of the present invention is the provision in hammer mills of a hammer with a removable tip which will'efect a considerable saving in the operation of the mill.

A very important object of the present invention is the provision of a mill hammer made in two separate parts, the main part of which will give a considerably prolonged service.

Still another important object of the present invention is the provision of a mill hammer having a removable tip which provides the shock absorbing surface of the hammer, 'said tip being readily removed and replaced without having to dismantle the mill housing and to dismount the whole hammer from the mill.

Yet another important objectof the present invention is the provision of a mill hammer having a removable tip wherein the fastening means between the tip and the body of the hammer are of novel and improved construction effecting a very secure attachment which will not be affected by the impacts or shocks received by the hammer.

The foregoing and other important objects of the present invention will become more apparent during the following disclosure and by referring to the drawings in which:

Figure 1 is a cross-sectional elevation of a hammer mill with hammers according to the invention;

Figure 2 is an enlarged elevation of the hammer according to the invention;

5 Claims. (Cl. 241-197) Figure 3 is a cross-section along line 3-3 of Figure 2; A

Figure 4 is a section along line 1l-Ll of Figure 3;

Figure 5 is a cross-section along line 5--5 of Figure 2; and

Figure 6 isan end view partly in section along line 6--6 of Fig. 2.

Referring now more particularly to the drawings in which like reference characters indicate like elements throughout, Figure -1 represents one type of hammer mill in which may be used the hammers, according to the invention. Said hammer mill comprises a horizontal shaft l rotating at high speed, on which is keyed a drum or disc bearing equally spaced stub shafts 3 pivotally mounting the swinging hammers generally indicated at said hammers being of the improved construction according to the invention;- Y

The bottom of the mill housing is provided with a cylindrical screen placed under the hammers and preferably constituted by a plurality of grate bars, the spacing of which may* or may not be adjustable,y to let through crushed particles of the desired sizeor mesh.

The ore is fed into the mill through a suitable aperture 6 and is crushed by the working face of the rotating swinging hammers 4 until it passes between the grate bars 5.

The hammer 4, according to the invention, comprises an eye l for looselyV receiving the stub shaft 3, said eye 'l being connected to the main body 8 through the intermediate of a neck 9.

The main body 8 and the removable tip I8, when fastened together, have a more or less rectangular overall shape except for the outer side working face4 I l of the tip l Il, whichiiiares slightly outwardly from the neck 9, and :the outer side face l2 of the body 8, which is bevelled at i3.

Furthermore, the hammer' 4 has preferably a rectangular cross-section as shown in Figure 5.

The removable tip li), according to the invention, has a substantially triangular shape and its inner side face adapted to contact the body 9 has a step-likerformation dening' two tongues and grooves |74 and l5 respectively, extending transversely of said face and adapted to engage and receive respectively similar co-operating grooves and tongues made in the contact face' of the body 8. The tongues I4 extend from root to tip longitudinally of the contacting -faces and outwardly from the eye l, whereby the centrifugally de veloped outward radial thrust of the tip lll will be transferred to the body 3. The general line ci separation of the body 8 and of the removable tip IU will be substantially inclined relatively to the longitudinal axis of the hammer according to the invention so that the thrust or shock received by the tip I will be absorbed to a substantial degree by these tongue and groove attachments. To further reinforce the fastening of the tip to the body, said body is provided with a longitudinally extending dovetail projection I6 made at the contact face of the body intermediate the two groove and tongue attachments. The dovetail projection I6 will engage a correspondingly shaped recess I1 made at the contact face of the removable tip I0.

The upper small end of the tip I0 is provided with a recess I8 aligned with a bore I9 made in the neck 9 of the main body 8, said'bore opening at its other end into the recess made in the neck 9 and part of the eye 1 of the hammer. The longitudinal axis of the bore I9 extends preferably at an angle relatively to the longitudinal axis of the hammer and at right angles to the contacting faces of the body I and removable tip I0.

A wedge bolt 2I is inserted through the bore I9 with its larger end 22 abutting against the curved bottom 23 of the recess I8 of the tip I0 and having its other end threaded to receive the nut 24 which is preferably a stop nut such as manufactured by the Elastic Stop Nut Corporation of America under the trade name of Esna, said nut housing a fiber washer frictionally engaging the threads of the bolt 2 I.

Upon tightening the nut 24, the head 22 of the bolt 2I will press down against the tip I0 and thereby will urge engagement of the co-operating tongues and grooves I4 and I5 at the contacting faces of the removable tip I0 and body 8. It will be noted that the nut 24 is substantially completely enclosed in the recess 20 thereby preventing injury to the same.

In order to allow free engagement of the wedge bolt 2I into the bore I9 the latter is provided with a longitudinal recess 25 extending at the bottom of said bore I9 from the contacting face of the body 8 to approximately the middle portion of said bore and with a second top recess 26 extending from the recess 20 downwardly past the middle portion of said bore I9.

The side edges of the working face II of the tip I0 are preferably rabbetted as shown at 21 to prevent chipping of said tip I0. Similarly the lower inner corner of the tip I0 at the contacting face of the same is preferably bevelled as shown at 28 together with the lower corner 29 of theoutside face I2 of the main body 8. The outer large end face 30 of the working tip I0 forms the base of said triangular tip and is substantially flush with the outer end face 3| of the body 8.

In practical experiments with thehammer, according to the invention, the removable tip I0 has been replaced at least twenty times without having to change the main body of said hammer, thereby increasing the life of said body twenty times relatively to a conventional mill hammer.

Furthermore, it has been found that the attachment described hereabove is very secure, no breakdown of the bolt 2I having ever occurred.

An advantage, according to the invention, is that the removable tip I0 may be easily replaced without having to dismantle the housing of the hammer mill. Therefore, the time of stoppage of the hammer mill is reduced to a minimum.

While a preferred embodiment according to the invention has been illustrated and described it is understood that various modifications may be resorted to without departing from the spirit and scope of the appended claims.

I claim:

1. A mill hammer of the swinging type comprising a main body adapted to be supported at its inner end, integral fastening means formed on a side face of said body, a removable working tip for said hammer of substantially triangular shape, integral complementary fastening means formed on one of the side faces of said removable tip to removably interlock with the fastening means on said side face of said body, a bolt extending through said tip and said body to prevent disengagement of said interlocking fastening means, the contacting faces of said main body and said removable tip extending at an angle relatively to the longitudinal axis of said hammer and at an angle relatively to said bolt, the outer end face of said working tip Yforming the base of said triangular tip and being substantially ush with the outer end face of said body.

2. A mill hammer of the swinging type, comprising an elongated main body, an eye rigidly dependent from said main body at one end, integral fastening means Vformed on, a face of said body, said face extending at an angle relatively to the longitudinal axis of said body, a removable working tip for said hammer of substantially triangular shape-integral complementary fastening means` formed on one side face of said removable tip to removably interlock with the fastening means of said body, a wedge bolt extending through said tip and said body adjacent said eye to urge engagement of said interlocking fastening means, said working tip being lbevelled at its corner adjacent to the contacting face of said main body and away from said eye.

3. A mill hammer of the swinging type comprising an elongated main body, an eye rigidly dependent from one end of said main body, said body having a contacting face extending at an angle relatively tothe longitudinal axis of the same, a triangular shaped removable working tip for said hammer, having a side face adapted to contact the contacting face of said body, the contacting faces of said main body and of said working tip having a step-like formation dening interlocking tongues and grooves extending transversely of said contacting faces, said 4contacting faces further provided with a dovetailed projection and corresponding recess extending longitudinally thereof between said transverse tongues and grooves, and a wedge bolt extending through said tip and said body to urge engagement of said tongues and grooves.

4. A mill hammer of the swinging type comprising a main elongated body adapted to be supported at one end, integral fastening means formed on a face of said body, said face extending at an angle relatively to the longitudinal axis of said body, a removable working tip for said hammer of substantially triangular shape, integral complementary fastening means formed on one side face of said removable tip to removably interlock with the fastening means of said body, and a bolt extending through the small end of said tip and said body adjacent said supported end to maintain engagement of said interlocking fastening means.

5. A mill hammer comprising a main body adapted to be supported at its inner end. a removablev working tip for said hammerbf substantially triangular shape, having aside face contacting one side face of said main body, integral interlocking means including transverse tongues engageable with complementary trans- UNITED STATES PATENTS verse grooves formed on the contacting side Number Name Date face of said body and a dovetailed projection 795,133 Johnson July 18, 1905 and corresponding recess extending longitudinal- 1,630,021 Lucas May 24, 1927 1y of said contacting faces between said 2,467,865 Smith Apr. 19, 1949 tongues and grooves, whereby said interlocking 10 2,534,301 Sennholtz Dec. 19, 1950 means become engaged upon outward longitu- 2,534,302 Sennholtz Dec. 19, 1950 dinal displacement of said working tip relatively to said body with their contact faces sliding upon FOREIGN PATENTS each othen Number COuDtl'y Date 5 6 spaced tongues formed on said side face of said REFERENCES CITED Workmg up extendmg from root to up longl' The following references are of record in the tudinally of said side face of said working tip and towards the outer end of the latter, said me of thls patent' CHARLES LE BLANQ 15 231,016 Great Britain Mar. 26, 1925 

